2 # Detect instances of "if (p) free (p);".
3 # Likewise for "if (p != NULL) free (p);". And with braces.
5 my $VERSION = '2008-02-11 08:08'; # UTC
6 # The definition above must lie within the first 8 lines in order
7 # for the Emacs time-stamp write hook (at end) to update it.
8 # If you change this file with Emacs, please let the write hook
9 # do its job. Otherwise, update this string manually.
11 # Copyright (C) 2008 Free Software Foundation, Inc.
13 # This program is free software: you can redistribute it and/or modify
14 # it under the terms of the GNU General Public License as published by
15 # the Free Software Foundation, either version 3 of the License, or
16 # (at your option) any later version.
18 # This program is distributed in the hope that it will be useful,
19 # but WITHOUT ANY WARRANTY; without even the implied warranty of
20 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 # GNU General Public License for more details.
23 # You should have received a copy of the GNU General Public License
24 # along with this program. If not, see <http://www.gnu.org/licenses/>.
26 # Written by Jim Meyering
32 (my $ME = $0) =~ s|.*/||;
34 # use File::Coda; # http://meyering.net/code/Coda/
36 defined fileno STDOUT or return;
37 close STDOUT and return;
38 warn "$ME: failed to close standard output: $!\n";
45 my $STREAM = ($exit_code == 0 ? *STDOUT : *STDERR);
48 print $STREAM "Try `$ME --help' for more information.\n";
53 Usage: $ME [OPTIONS] FILE...
55 Detect any instance in FILE of a useless "if" test before a free call, e.g.,
56 "if (p) free (p);". Any such test may be safely removed without affecting
57 the semantics of the C code in FILE. Use --name=FOO --name=BAR to also
58 detect free-like functions named FOO and BAR.
62 --list print only the name of each matching FILE (\0-terminated)
63 --name=N add name N to the list of `free'-like functions to detect;
66 --help display this help and exit
67 --version output version information and exit
77 For example, this command prints all removable "if" tests before "free"
78 and "kfree" calls in the linux kernel sources:
80 git ls-files -z |xargs -0 $ME --name=kfree
91 my $err = EXIT_NO_MATCH;
97 help => sub { usage 0 },
98 version => sub { print "$ME version $VERSION\n"; exit },
103 # Make sure we have the right number of non-option arguments.
104 # Always tell the user why we fail.
106 and (warn "$ME: missing FILE argument\n"), usage EXIT_ERROR;
108 my $or = join '|', @name;
109 my $regexp = qr/(?:$or)/;
111 # Set the input record separator.
112 # Note: this makes it impractical to print line numbers.
117 foreach my $file (@ARGV)
120 or (warn "$ME: can't open `$file' for reading: $!\n"),
121 $err = EXIT_ERROR, next;
122 while (defined (my $line = <FH>))
125 /\b(if\s*\(\s*(\S+?)(?:\s*!=\s*NULL)?\s*\)
126 (?: \s*$regexp\s*\(\s*\2\s*\)|
127 \s*\{\s*$regexp\s*\(\s*\2\s*\)\s*;\s*\}))/sx)
131 and (print "$file\0"), next FILE;
141 $found_match && $err == EXIT_NO_MATCH
142 and $err = EXIT_MATCH;
148 # The above is to *find* them.
149 # This adjusts them, removing the unnecessary "if (p)" part.
151 # FIXME: do something like this as an option (doesn't do braces):
152 git ls-files -z |xargs -0 \
153 perl -0x3b -pi -e 's/\bif\s*\(\s*(\S+?)(?:\s*!=\s*NULL)?\s*\)\s+(k?free\s*\(\s*\1\s*\))/$2/s'
155 useless-if-before-free -l $(lid -knone free) | xargs -0 \
157 's/\bif\s*\(\s*(\S+?)(?:\s*!=\s*NULL)?\s*\)\s+(free\s*\(\s*\1\s*\))/$2/s'
159 Be careful that the result of the above transformation is valid.
160 If the matched string is followed by "else", then obviously, it won't be.
162 When modifying files, refuse to process anything other than a regular file.
166 ## indent-tabs-mode: nil
167 ## eval: (add-hook 'write-file-hooks 'time-stamp)
168 ## time-stamp-start: "my $VERSION = '"
169 ## time-stamp-format: "%:y-%02m-%02d %02H:%02M"
170 ## time-stamp-time-zone: "UTC"
171 ## time-stamp-end: "'; # UTC"